[sdiy] electrosensitive devices

[patchell]

    When I worked at Hughes Aircraft, the 3M people gave a demonstration (a
sales pitch for their anti static equipment and materials), where they measured
the gate leakage of a FET, then put it into a "pink" anti static bag, and 1 foot
away from the back, pulled about 1 foot of scotch tape off a tape dispenser.
They then put the fet back into the leakage tester to show that the gate had be
severly damaged.  So the answer is that you do not need to see a spark in order
for the there to be static damage.

Stephen Begin wrote:

> One more question about static then...is it possible for a significant
> amount of static to transfer from say...my finger to an expensive cmos chip,
> without that audible "zap" sound?
> -steve
>
> ----- Original Message -----
> From: "Peter Grenader" <petergrenader at mksound.com>
> To: "Stephen Begin" <trypannon at hotmail.com>; "synth"
> <synth-diy at dropmix.xs4all.nl>
> Sent: Friday, April 04, 2003 10:43 PM
> Subject: Re: [sdiy] electrosensitive devices
>
> >
> > Many suppliers, Mouser among them, put a blanket control system on all
> > semiconductors.  It's less expensive for them to put all semi's into the
> > costly nickel plated anti static bags than it is to concoct some large
> scale
> > sorting/segregation system, because it has to carry not only to the final
> > shipment, but through their entire warehousing/receiving system as well.
> > You can only imagine how hard it would be to assure that all static
> > sensitive parts, and only those parts, received special handling
> procedures,
> > are kept in a separate stores locations, etc.
> >
> > So,  if you are unsure which are and are not problematic for static, as
> > impractical as this may be, the best solution would be to carry out their
> > system in your lab and for you to treat everything as static sensitive as
> > well.   Yeah, I know...a drag.
> >
> > Problem is, and this came up a few months ago...99.99999999 to the tenth %
> > of the failures from the initial static discharge is not catastrophic.  It
> > merely degrades the part so it will lean towards infant mortality
> somewhere
> > down the road.  And when it does, it's hard to determine if ESD was the
> > cause unless you pop the top off and have a look under an extremely
> powerful
> > microscope. Even more impractical in my book.
> >
> > Two general rules of thumb will help you out a lot:
> >
> > 1)  Treat static like a virus and take the necessary precautions to keep
> it
> > from spreading.
> >
> > 2)  Get your hands around which parts are and are not susceptible and make
> > damn sure you at least keep them in foam when not in boards and wear a
> > ground strap when inserting them or when handling a board that has them
> > inserted, even if you are planning of fooling with those parts directly at
> > the time.
> >
> > I worked for a company (Western Digital) whose first products were
> > controller LSI chips.  This is what they started off doing and what put
> them
> > on the map. This was years before they purchased the Tandon hard drive
> > division. You have no idea what you have to go through to create a truly
> > static free environment.  We're talking heels straps, nickel faraday bags,
> > heel straps, wrist wraps, conductive booties, grounded forklifts, grounded
> > storage racks, grounded soldering irons, air ionizers, conductive mats,
> > anitstatic spraying of work benches - it's a complete mess.
> >
> > hope this helps - remember, it's not only 4000 series CMOS you have to
> worry
> > about!
> >
> > Peter
> >
> >
> >

--
 -Jim
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